In the spectral classification system (O, B, A, F, G, K, M), which class represents the hottest stars?

Answer

O-type

The spectral classification sequence moves from hottest to coolest as O, B, A, F, G, K, and M. O-type stars sit at the very top of this thermal ladder.

In the spectral classification system (O, B, A, F, G, K, M), which class represents the hottest stars?
astronomytemperaturestarshottest